If a washer had 3 legs that pointed out & back, you could run that up in the pipe & the legs ( given they are made of stiff, hard wire) wouldnt back out the pipe.
Go to a hobbyshop & ask for piano wire. Be careful cutting it & bending it in a small radius. Its so hard it breaks sometimes, in the sizes above 1/16th. It can screw up cheap diagonals,too.

Not sure how it will behave after being brazed on. You may have to quench it. Or not?

that has been testes and will help in making power


EVERybody wants an exhaust system that really has balls..

Most likely nobody wants to hear it, but the issue is not "back pressure." If it were, the easiest way to do it would be to make the exhaust valve very small and the exhaust pipe very small diameter. Instead, the pipe acts like a resonant system, with pressure waves bouncing around in it. The reason a straight pipe is hard to tune is because it is resonant only at one frequency (speed), and at any other speed it doesn't work correctly. A smaller diameter pipe has a bit more "resistance" which helps broaden the peak. In electronic terms it has a higher resistance and thus less "Q." Those pressure waves will help or hinder engine breathing depending on engine speed, and during the valve overlap they may even influence the intake tract. Note that the intake tract can also be resonant, and its resonant frequency is almost certainly different from the exhaust. It is easy to say the engine needs back pressure, but it is nowhere near the whole truth.

It is a little difficult to find concrete numbers, but as far as I can tell a four-stroke engine, operating at wide-open throttle, will have a cylinder pressure on the order of 50 psig when the exhaust valve first cracks open. That relatively high pressure is why the exhaust valve is smaller than the intake - there is more pressure differential to get the gas moving than on the intake side.

justin_o_guy2 wrote on 07/29/09 at 19:28:39:


No diff to the layman.  
psi (pounds per square inch) is the same as psig(pounds per square inch gage) reading.
Why is there psig?  cause there's a psia (pounds per square inch absolute)  same as psig + atmospheric pressure, usually 15 psia or there abouts.

To be slightly more pedantic than Versy, pressure gauges actually measure differential pressure. That is, they measure the difference in pressure between the atmosphere (usually) and the inside of the container (such as a tire). PSI means Pounds per Square Inch. PSIG means PSI measured by a Gauge. Almost always PSI really means PSIG. PSIA means PSI Absolute, which is referenced to a vacuum. For most any sort of technical work you need to use PSIA, and you need to use temperatures measured from absolute zero (Kelvin instead of Celsius; Rankine instead of Fahrenheit).

justin_o_guy2 wrote on 07/29/09 at 19:45:19:

psig would be the pressure above atmospheric.
psia includes it.

Yep, you got it. With the caveat that you are at about sea level. To a rough approximation, atmospheric pressure drops about one PSI for every two thousand feet of elevation. So in some city at 6000 feet (Cheyenne, Colorado Springs) the atmospheric pressure is only 12 PSIA instead of the nominal 15 at sea level. There, a 30 PSIG tire would be 42 PSIA.